1. Technical Field
The present invention relates to the field of electronic medical technology. More particularly, the present invention relates to a portable and non-power supplied electronic device and method for monitoring the intravenous infusion dripping flow rate in real time and generating alarm signals for the irregularities of the intravenous infusion.
2. Related Art
Intravenous gravity infusions are widely used medical treatment, and especially seriously ill patient often require long hours of continuous monitoring by caregivers. When the infusion solution is depleted or some irregularities happen during the infusion processing, the caregiver need promptly notify a medical staff person to change the infusion solution or remove the needle from the intravenous vessel. Time is very essential for preventing the complications such as blood backflow or air bubbles trapped in the infusion tube, but the continual monitoring of the infusion solution level by people is extremely inconvenient and burdensome for the caregiver. It might be very danger if the caregiver neglects their duty, especially during the night when the caregiver may be drowsy. The infusion dripping rate is one of the most important parameters for intravenous therapy. There are stringent requirements for infusion rate among certain patients such as the elderly, pediatric patients or patients with cardiopulmonary diseases, as well as when special medical solution is used. Large variations of the infusion rate due to poor performance of the infusion device, human factors or equipment failures could happen during the infusion process, for example, patients arbitrarily tune fast the solution dripping rate during the infusion process, or the infusion control valve becomes loose, the infusion needle moves out of the intravenous vessel, the blood is clogged inside of the needle bucket, the infusion needle rotates in the venous, or the blood pressure changes during the infusion process. All these kind of scenario might lead to deleterious consequences, or even cause unconsciousness and death of the patients under severe conditions. To help combat this problem, a variety of alarm devices have been developed to monitor and control the infusion dripping rate in clinic.
The existing infusion monitoring technologies for infusion dripping rate (or flow rate) might mainly include ultrasound, Of optical perception technologies, or detecting the fluid levels of the intravenous infusion container as shown in Cohen (U.S. Pat. No. 5,135,485).
All the current intravenous infusion monitoring device have failed to create a feasible solution to make a small , portable, highly energy saved and ultra-sensitive intravenous infusion monitoring device be cable of detecting and displaying the intravenous infusion dripping flow rate in real time.
Devices based on ultrasound technology usually involve placing a pair of ultrasonic transceivers at both sides of the infusion dripping chamber. Based on the principle that solution droplets cause attenuation or refraction of ultrasound wave, a group of pulse signals of dripping solution are obtained, as a way to monitor the infusion rate. However, ultrasound monitoring device is hard to be implanted in small portable devices due to the obstacles in cost, size, power consumption and other aspects, but it usually be applied relatively large non-portable devices in some circumstances such as professional infusion pumps in hospital operation room, which are very expensive and requires high power consumption. These types of infusion pumps are not practical for the widely using in small family medical facility, military battlefield or refugee institution.
Device based on the optical perception technologies might involve placing optical transceivers at both sides of the dripping chamber. Taking advantage of the principle that droplets cause light attenuation and refraction during the dripping process, a group of pulse signals reflecting cycle of the dripping solution is obtained, as a way to monitor the infusion rate. However, the lightness perception devices have the following disadvantages: The optical transceivers might have to be protected from light and thus the dripping chamber where it transmit the light might need to be covered, and therefore it will hinder the visual operation and observation of the standard infusion through the dripping chamber, as well it cannot be effectively applied to the light-sensitive medical solution infusion. In additional, large amount of natural light, electric light and medical infrared light often interfere with the lightness perception monitoring process and it will reduce the accuracy of the monitoring infusion dripping rate; Plus, the need of continuous light emission requires high power consumption, which is not practical for certain infusion field condition. Some prior monitoring devices such as that described in U.S. Pat. No. 5,166,667 to Jen. This device uses control circuit for providing a light source for transmitting light through a wall of the drip chamber to each drop of fluid suspended from the end of the drip tube, and an optical system for receiving light transmitted through the drop and generating control signals to detect the flow rate of dripping in dripping chamber, which requires a light source to constantly illuminate the infusion solution during the infusion process.
Another example of the infusion fluid level sensing system is disclosed in U.S. Pat. No. 5,135,485 to Cohen et al. discloses an infusion fluid level sensing system by using a conductive plates attached the outside of the plastic infusion bag and connect to a circuit to detecting the change in the capacitance of the capacitor formed thereby due to the fluid level changes in the infusion bag during the infusion process. This device not only has the disadvantages inherent in a monitoring but also has several other problems in its implementation. The device has limited ability to accurately monitor the infusion flow rate by attaching the device to the infusion bag. It is well known that gravity infusion plastic bag size varies wildly and very deformable. In additional, it uses capacitance detector to detect the fluid level in the infusion bag and calculate the flow rate by monitoring the fluid level in the infusion bag, therefore the detected flow rate is very rough as well poor accuracy, and the infusion dripping rate is not capable to be detected and displayed in this device.